1. Field of the Invention
The invention relates to surgical instruments and, more particularly, to endoscopic surgical instruments useful to perform endoscopic discectomy procedures and other minimally invasive spinal procedures.
2. Description of the Related Art
Back pain is a common affliction affecting millions of people. In many instances, back pain is caused by a herniated intervertebral disc. Intervertebral discs are generally cylindrical-shaped structures corresponding to the margins of the adjacent vertebrae. An outer ring known as the annulus fibrosus composed of concentric layers of fibrous tissue and fibrocartilage surrounds a cartilage-like core known as the nucleus pulposus. When an intervertebral disc is herniated, the softer nucleus projects through a torn portion of the annulus, creating a bulge which extends beyond the intervertebral foramen. As a result of the bulging disc, various spinal nerves may be compressed, causing pain or numbness.
Various procedures are used to treat herniated intervertebral discs. In mild disc herniation, pressure on adjacent nerves is lessened through non-surgical techniques. Such techniques include drugs (analgesics, anti-inflammatory drugs, muscle relaxants), physical therapy, and rest. If these non-surgical approaches are not successful, surgical intervention is necessary. Various surgical procedures have been developed to remove at least a portion of the herniated disc. Such procedures include laminotomies, laminectomies, and percutaneous discectomy.
In laminotomy (also referred to as interlaminar exploration), a posterior approach is used to access the spine through a longitudinal incision. Small amounts of the bony spinal lamina are removed, allowing access to, and removal of, portions of the herniated nucleus pulposus.
Laminectomy is a surgical procedure which, like laminotomy, uses a posterior approach to the herniated disc. In laminectomy, a larger portion of the spinal lamina or laminae are removed to access and remove portions of a herniated disc nucleus. Because both laminotomy and laminectomy require removal of bone and retraction of nerves and muscles, hospitalization and recuperation periods are lengthy. Additionally, removal of bone may lead to future spinal instability.
To minimize the need to remove portions of the vertebrae, other approaches to the herniated disc have been used. In particular, percutaneous discectomy employs a postero-lateral approach. Instruments are inserted through a cannula inserted through the patient's side. The disc annulus is pierced and the herniated nucleus is mechanically disintegrated, the pieces being removed through suction. This technique is shown for example in U.S. Pat. Nos. 4,545,374, 5,242,439 and RE 33,258.
Endoscopic surgery involves incising through body walls via small incisions, generally by use of a trocar having a obturator with a sharp tip removably positioned in a cannula. After penetration, the obturator is removed leaving the cannula positioned in the body for reception of a camera or endoscope to transmit images to a remote TV monitor. Specialized instruments such as forceps, cutters, and applicators are inserted through other trocar sites for performing the surgical procedure while being viewed by the surgeon on the monitor. With the advent of endoscopic surgery and the recognition of its advantages over open procedures in reducing costs by shortening the patient's hospital stay and time of recovery so the patient can resume normal activity sooner, the industry has been viewing endoscopic discectomy as an alternative to the techniques and surgical methods described above. However, to date, the need exists for endoscopic instrumentation to properly and atraumatically improve access to the disc to facilitate removal for successful performance of endoscopic discectomy. The need also exists for improved endoscopic instrumentation to clear a path for removal of the disc as well as to excise the disc.
U.S. Pat. No. 5,195,541 discloses a method for performing lumbar discectomy involving inserting a sleeve having an endoscope receiving means, a laser fiber receiving means and a suction and irrigation channel means. This device, however, is of relatively large diameter because it must accommodate a variety of surgical instruments and therefore may obstruct the surgeon's view (on the TV monitor) and provide limited access to the disc.
There is a need in the art for improved surgical instrumentation which facilitates minimally invasive surgical techniques for anteriorly accessing the herniated disc. The instrumentation and techniques should improve both access to and removal of the disc and permit the surgeon to endoscopically remove any desired amount of disc material with minimal interference to spinal nerves and adjacent back muscles. Such instrumentation and techniques would permit the surgical alleviation of back pain while providing the benefits attendant endoscopic/laparoscopic surgery, namely avoiding large incisions and long periods of hospital stay and patient recovery.
Such instrumentation could also advantageously be used for aiding other minimally invasive surgical spinal procedures such as spinal fusion.